Rails - Apr 2006 - command rake migration also runs #down method ?

Hi,

i am new to rails and trying to understand the migrate feature of rake

whenever I call "rake migrate", i understand it call all the latest 
version of a given of given migrate files.

Now when these files are executed, id the #down method called and then 
the #up ? or must i explicitly call the #down method from rake. If yes 
how do i do that from rake ?

I experimented with rake migrate and could not update my database table 
i.e. chage a field from varchar(200) to varchar(200). i had to resort to 
the console commands appended (see below) for it to work.

Also say I have migration scripts of different versions say for table1 
it is version 5, table 7 version 4 etc
if I run rake migrate will it run both v5 for both tables or will it run 
v4 for one and v5 for the other ? This is still not clear to me...

TIA,
Tuka



C:\TDV>ruby script/console
 Loading development environment.
 >> require ''db/migrate/001_test_migration.rb''
 => true


 >> TestMigration.down
 == TestMigration: reverting 
================================================== --
drop_table(:migration_test)
    -> 0.0900s
 == TestMigration: reverted (0.0900s) 
=========================================

 => nil
 >> TestMigration.up
 == TestMigration: migrating 
================================================== --
create_table(:migration_test)
    -> 0.1200s
 == TestMigration: migrated (0.1200s) 
=========================================

 => nil
 >>

-- 
Posted via http://www.ruby-forum.com/.

Here''s the way it is supposed to work.

1. Rake looks at your database, there should be a table there that  
contains one column and one row that indicates the current version of  
the database schema

2. Rake will then look through your migrations folder and looks at the  
number in the migration file names.

3. For each file with a number greater than the current database schema,  
rake will call ''up''

4. When you are degrading to an earlier version, rake will call
''down''
for each migration file until the database schema version matches the  
migration file number.

The database only has one version number, which is the accumulation of  
all the migrations up to that point.  In many ways it is similar to  
subversion''s revision number.

On Tuesday, April 25, 2006, at 3:05 PM, Tuka Opaleye
wrote:
>Hi,
>
>i am new to rails and trying to understand the migrate feature of rake
>
>whenever I call "rake migrate", i understand it call all the
latest
>version of a given of given migrate files.
>
>Now when these files are executed, id the #down method called and then
>the #up ? or must i explicitly call the #down method from rake. If yes
>how do i do that from rake ?
>
>I experimented with rake migrate and could not update my database table
>i.e. chage a field from varchar(200) to varchar(200). i had to resort to
>the console commands appended (see below) for it to work.
>
>Also say I have migration scripts of different versions say for table1
>it is version 5, table 7 version 4 etc
>if I run rake migrate will it run both v5 for both tables or will it run
>v4 for one and v5 for the other ? This is still not clear to me...
>
>TIA,
>Tuka
>
>
>
>C:\TDV>ruby script/console
> Loading development environment.
> >> require ''db/migrate/001_test_migration.rb''
> => true
>
>
> >> TestMigration.down
> == TestMigration: reverting
>==================================================> --
drop_table(:migration_test)
>    -> 0.0900s
> == TestMigration: reverted (0.0900s)
>=========================================>
>
> => nil
> >> TestMigration.up
> == TestMigration: migrating
>==================================================> --
create_table(:migration_test)
>    -> 0.1200s
> == TestMigration: migrated (0.1200s)
>=========================================>
>
> => nil
> >>
>
>--
>Posted via http://www.ruby-forum.com/.
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>Rails mailing list
>Rails@lists.rubyonrails.org
>http://lists.rubyonrails.org/mailman/listinfo/rails

_Kevin

-- 
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> Now when these files are executed, id the #down method called and then 
> the #up ? or must i explicitly call the #down method from rake. If yes 
> how do i do that from rake ?
Down method should only be called when you are migrating to an earlier 
version of the schema via:

rake migrate VERSION=12


-- 
Posted via http://www.ruby-forum.com/.

That would explain my dificulty with rake migration. thanks a lot.

Cheers,
Tuka

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